https://www.amazon.com/120-Year-Diet-Double-Vital/dp/0671466...

Those folks were disdainful of "one-mouse experiments" but Roy was vital and productive for a long time and passed at 79 from ALS which is one of the worse ways you can go and used a lot of weed

https://en.wikipedia.org/wiki/Roy_Walford

I can say that when I was lowballing my calories I was often uncomfortable, particularly in the cold. If I could keep the temperature constant it might not be so hard but in an old farmhouse in NY it's pretty hard even if you are strategic about long underwear and other warm programming. But yeah, the average American could use to eat a bit less and so I could I.